The flow generating box rested rigidly on an aluminum frame. The exit velocity was monitored via a pressure tap in the nozzle positioned upstream of the contraction and connected to a digital manometer by a silicon tube. The ambient pressure was monitored by an independent barometer. The air intake was located inside the jet enclosure so that both jet and ambient are seeded to provide as homogeneous a seeding distribution in the measured flow as possible. The seeding particles were generated from liquid Glycerin using an atomizing nozzle built in-house, providing tracers with a typical size of about \(2-3 \, \mu m\) . The enclosure consisted of a large tent of dimension \(2.5 \times 3.0 \times 4.5\, m^3\) , yielding a cross-sectional area of \(2.5 \times 3.0\, m^2\)  that resulted in a momentum conservation of \(100.0\%\)  at \(x/D_0 = 30\)  and \(98.4\%\)  at \(x/D_0 = 100\) , where \(x\)  is the downstream distance from the jet exit [1]}.
